Hard disk drive (HDD) systems typically include one or more data storage disks with concentric tracks containing information. A transducing head carried by a slider is used to read from and write to a data track on a disk, wherein each slider has an air bearing surface that is supportable by a cushion of air generated by one of the rotating disks. The slider is carried by an arm assembly that includes an actuator arm and a suspension assembly, which can include a separate gimbal structure or can integrally form a gimbal.
In more particularity, many disk drives include a transducer that “flies” only a few nanometers above a rotating disk surface. The transducer is mounted in a slider assembly which has a contoured surface. When the disk is at rest, the air bearing slider is in contact with the disk. During operation, the disk rotates at high speed, and an air bearing force is produced by pressurization of the air as it flows between the disk and slider. This air force acts upon a lower air bearing surface of the slider and generates a lift force directing the slider away from the disk and against a load beam causing the slider to fly at an ultra-low height above the disk. Thus, the air force prevents unintentional contact between the transducer and the disk and also provides a very narrow clearance between the slider transducer and the rotating disk. This allows a high density of magnetic data to be transferred and reduces wear and damage. The height at which the read/write head of a slider is positioned above a rotating disk when no reading or writing is taking place is known as the passive fly height, which height is decreased to an operational clearance when reading and/or writing is taking place
Because the demand for disk storage systems with large storage capacities is increasing, the density of concentric data tracks on disks is increasing, which in turn requires that the air bearing gap between the transducing head and the rotating disk be reduced to even lower flying heights. During operation of the magnetic data storage and retrieval system, the transducing head is positioned in close proximity to the magnetic media. A distance between the transducer and the media is preferably small enough to allow for writing to and reading from a magnetic medium, and great enough to prevent contact between the magnetic media and the transducer. As the average flying height of the slider decreases, the transducer achieves greater resolution between the individual data bit locations on the disk. Therefore, operational flying height or clearance is one of the most critical parameters of magnetic recording for drive performance and reliability.
Detection of head-media contact is one known method of establishing head-media spacing in a storage system. This can be accomplished by determining a zero reference using an actuator to make the head contact the disk. However, contamination on the head can cause an early contact detect trigger, which leads to an incorrect zero reference being used as the clearance setting. Such contamination can particularly be an issue with heat-assisted magnetic recording (HAMR) processes due to elevated head and media temperatures. Thus, a need exists for consistently removing head contamination at each heat actuator power step in systems that use heat-assisted magnetic recording (HAMR) processes.